I.

Introduction

Ballooning, use of lighter-than-air craft known as balloons. Balloons consist of a large flexible bag containing either hot air or a gas that is lighter than air. The bag, known as an envelope, is made of varnished silk, rubber, or other suitable material. Piloted balloons carry one or more persons in a suspended gondola; unpiloted balloons are usually used for scientific research and carry instruments to measure and record a variety of physical phenomena.

Any gas that is lighter than air can be used to lift a balloon. Hydrogen, helium, methane, ammonia, natural gas, manufactured gas (gas made from soft coal or petroleum products), and heated air can and have been used to fly balloons. The earliest balloons were filled with hot air and often carried a brazier (metal container for burning coal or charcoal) to continuously heat the air. Modern balloons are usually filled with hydrogen or helium or air heated by a small gas burner. Helium has the great advantage of being nonflammable (difficult to burn or ignite), unlike hydrogen, which is flammable.

Balloons are used primarily for two purposes: sport or scientific research. Sport balloons mostly use hot air. They range from 10 to 20 m (33 to 66 ft) in size when the envelope or bag is inflated. Scientific balloons generally use hydrogen, helium, methane, or ammonia. They range in size from 30 to 200 m (100 to 660 ft) when fully inflated.

II.

History of Ballooning

A.

Early Balloons

The first practical hot-air balloon was invented in 1782 by two French brothers, Jacques Étienne and Joseph Michel Montgolfier, wealthy papermakers of Annonay, France. In a second balloon flight in June 1783 the two men sent up a paper-lined linen balloon that rose 1,800 m (6,000 ft). In August of the same year the French physicist, chemist, and aeronaut Jacques Alexandre César Charles released a balloon filled with hydrogen, which made a successful two-hour flight, covering 43 km (27 mi). In November the first piloted flight occurred when the French physicist Jean François Pilâtre de Rozier and his companion, the Marquis D’Arlandes, ascended in a hot-air balloon built by the Montgolfier brothers, from the Bois de Boulogne, a park in Paris. Rozier’s first ascent was in a balloon with ropes attached to the ground. Later he went up in a free balloon without ropes. In December the first piloted flight in a hydrogen-filled balloon was made from the Tuileries gardens in Paris.

By the end of 1783 balloon mania had taken over in France and soon spread throughout the continent and England. Cities vied with each other to build the biggest or prettiest balloons and to fly higher and longer. Hot-air balloons were more maneuverable, but the hydrogen balloons flew for longer periods. In 1785 Rozier attempted to cross the English Channel in a balloon combining a hydrogen-filled bag above a hot-air balloon. The hydrogen caught fire, and Rozier and his copilot were killed. The balloon design, called a Roziere, was rarely used for the next 200 years but its revival made history, enabling balloonists to circumnavigate the globe for the first time.

In 1785 the French aeronaut Jean Pierre Blanchard, accompanied by John Jeffries, an American, made the first balloon crossing of the English Channel. Blanchard also made the first balloon ascent in North America, from Philadelphia, Pennsylvania, in 1793. The next century saw the use of balloons flourish for sport and celebration. In 1836 The Great Balloon of Nassau, with a capacity of 2,410 cu m (85,000 cu ft), sailed 800 km (500 mi) from London to Weilburg, Germany, in 18 hours.

B.

Military Use of Balloons

During the Franco-Prussian War (1870-1871), balloons were used for military observation by the armies of both nations. The French statesman Léon Gambetta made a dramatic escape from the besieged city of Paris by balloon.

Armies in World War I (1914-1918) made extensive use of balloons, especially for military observation. The balloons were tethered (controlled by ropes) and used to observe enemy lines. They were quickly lowered when enemy aircraft were sighted. Allied and German pilots received medals for shooting down observation balloons.

During World War II (1939-1945) the barrage balloon (a large fabric balloon tethered to a steel cable) was used extensively to protect London from low-level air attacks. The barrage balloons were tethered in rows at altitudes up to 1,000 m (4,000 ft) to provide a barrier against enemy bombers attacking London. Also during World War II, Japan launched over 9,000 Fu-Go balloons in 1944 and 1945. These were 10-m (33-ft) laminated paper spheres inflated with hydrogen. A timing mechanism periodically dropped ballast (stabilizing heavy weights) to maintain the balloon near the jet stream (the wind that travels from west to east in the upper atmosphere). The balloons carried incendiary bombs and one high-explosive bomb. Only 10 percent of the balloons reached the West Coast of the United States, and most of these landed in the Northwest during the rainy season and caused little fire damage.

Balloons were also used during the Cold War. For a brief period the United States Air Force flew several hundred balloons equipped with cameras over the Soviet Union. A timer controlled the release of the cameras. Once released, the balloons rose rapidly and destroyed themselves in the atmosphere. The cameras descended by parachute over the Pacific Ocean, and U.S. Navy vessels recovered them. After the late 1960s high-flying aircraft and satellites replaced balloons in performing this reconnaissance.

C.

Scientific Use of Balloons

In 1803 the first scientific balloon flight—to make measurements of electricity in the air—reached an altitude of 7,400 m (24,300 ft). A year later French chemist and physicist Joseph Louis Gay-Lussac made measurements of the composition of the air by using a balloon. Throughout the 19th century and into the 20th century, the balloon was the only vehicle available for atmospheric measurements. Scientists risked their lives flying to higher altitudes to conduct their experiments. In 1931 the Swiss physicist Auguste Piccard ascended into the stratosphere in a spherical, airtight, metal cabin suspended from a specially constructed hydrogen-filled balloon of 14,000 cu m (494,400 cu ft) capacity, reaching an altitude of 15,797 m (51,793 ft). The following year he reached 16,940 m (55,577 ft).

In 1935 two U.S. Army captains, Orvil Anderson and Albert William Stevens, ascended to 22,080 m (72,440 ft). The primary purpose of this flight was to determine how the makeup of the atmosphere changed with altitude by obtaining air samples in the stratosphere. In 1957 Major David Simons, a U.S. Air Force surgeon, ascended to about 31,110 m (about 102,000 ft), remaining in the air 32 hours. Simons’s flight was designed to study the physiological reactions of humans at high altitudes. In 1960 Captain Joseph Kittinger of the U.S. Air Force bailed out of a polyethylene plastic balloon at 31,354 m (102,867 ft), setting a new altitude record for balloon flight and a new record for parachute descent. In 1961 Malcolm Ross, a U.S. Navy commander, and Victor Prather set an altitude record of 34,679 m (113,776 ft).

D.

Ballooning as a Sport

Sport ballooning is ballooning for fun, adventure, or competition, as opposed to ballooning for scientific, commercial, or military purposes. The Gordon Bennett Balloon Trophy Races, named for the American journalist James Gordon Bennett who donated the trophy, stimulated interest in ballooning as a sport. Competitions were held annually from cities in Europe and the United States from 1906 to 1938, except during World War I. The Gordon Bennett Aeronautic Cup was awarded to the balloonists who flew farthest and for the longest duration.

Sport ballooning still enjoys limited popularity in Europe. Beginning in the 1960s hot-air balloons replaced hydrogen-filled balloons in sport ballooning. Hot-air ballooning became a safe and accessible sport with the availability of rip-stop nylon for the envelope and propane burners to heat the air. The first flight of a modern hot-air balloon was made in 1960 from Bruning, Nebraska. In the United States balloon festivals are conducted in dozens of cities, the largest being the Albuquerque International Balloon Fiesta, held each October in Albuquerque, New Mexico. This event was started in 1971 and with its size, color, and spectacle helped popularize the sport.

E.

Ballooning Records

The helium-filled Double Eagle II, piloted by the American businessmen Ben L. Abruzzo, Maxie L. Anderson, and Larry Newman, made the first successful transatlantic balloon flight in August 1978. The balloon took off from Presque Isle, Maine, on August 11 and landed in Miserey, France, on August 17, setting a distance record of 5,000 km (3,000 mi) and an endurance record of 137 hours 6 minutes. Two Americans, Troy Bradley and Ben Abruzzo’s son Richard, broke the endurance record in 1992. After taking off from Bangor, Maine, in the world’s first transatlantic race, they were blown off course and landed near Fès, Morocco, 146 hours later. Kittinger made the first solo transatlantic crossing in 1984 when he flew his helium-filled Rosie O’Grady’s 5,690 km (3,535 mi) from Caribou, Maine, to the Italian Riviera near Savona. All of these sport-ballooning flights were made with a zero-pressure balloon, a balloon with an envelope made of plastic that is filled only partly with gas while on the ground. As the balloon ascends, a lifting gas, usually helium, fills the envelope.

E.1.

Long-distance records

With the conquest of the Atlantic, the next major challenge for balloon adventurers was to circumnavigate the globe. The zero-pressure balloon with its maximum duration of seven days could not be used for a flight that would take at least two weeks. The English balloon manufacturers, Lindstrand Balloons Ltd. and Cameron Balloons Ltd., both determined that the Roziere balloon, a 200-year-old concept of combining a bag filled with lighter-than-air gas and a hot-air balloon, would last the necessary two weeks. The Lindstrand Roziere balloons consisted of a spherical helium bag with a hot-air cone attached below it. The hot air in the cone heated the helium bag to provide lift, and additional lift was obtained from the heated air in the cone. The Cameron Roziere balloons used a helium bag covered by an outer shell that was separated from the helium bag by a small balloon on top. Hot air flowed over the entire bag when the burners were ignited.

The burners on the Roziere-type balloons were used to maintain altitude at night when helium in the gas bag cooled, becoming denser, and therefore tending to cause the balloon to sink. Changing altitude to take advantage of more favorable winds or to avoid bad weather was accomplished by heating air to ascend or releasing helium gas to descend.

In 1997 the Anheuser-Busch Corporation provided a financial incentive by announcing a $1-million prize for the first piloted balloon to circumnavigate the globe without landing. Several teams of balloonists attempted to win the prize using Roziere balloons designed by Cameron. Three attempts were made in Lindstrand-designed Roziere balloons.

In March 1999 Swiss psychiatrist Bertrand Piccard, grandson of famed balloonist and physicist Auguste Piccard, and British pilot Brian Jones became the first persons to succeed, claiming the $1-million prize. Their journey in the Breitling Orbiter 3, a Cameron Roziere balloon, lasted 19 days 21 hours. The balloon was launched from Switzerland. With excellent wind forecasts and skillful piloting, both of which enabled the balloonists to take advantage of favorable winds, the two men circled the Earth from west to east, landing in Egypt.

In July 2002 American investment executive Steve Fossett became the first person to circle the world on a nonstop solo flight, using a Cameron Roziere balloon. His journey in the Spirit of Freedom lasted 14 days 20 hours, traveling 33,972 km (21,109 mi) from Kalgoorlie, Australia, to Queensland in northeastern Australia.

E.2.

Altitude Records for Hot-Air Balloons

The record for the highest hot-air balloon ascent was set in November 2005 by Indian businessman and aviator Vijaypat Singhania, who climbed to 21,291 m (69,852 ft) in a pressurized cabin attached to a 48.8 m (160 ft)-high balloon. The previous record was held by Per Lindstrand, a Swede, who ascended to 19,811 m (64,997 ft) in 1988.

III.

Modern Scientific Ballooning

Balloons are used in a variety of scientific research. Three types of balloons are commonly used: rubber balloons; the zero-pressure, plastic balloons; and the superpressure, sealed balloons.

A.

Rubber Balloons

The rubber, or neoprene, balloon is used to take vertical measurements of the atmosphere as the balloon rises. It uses a radiosonde, an instrument for gathering and transmitting meteorological data from the upper atmosphere, such as wind speed and direction. The balloon is inflated with a lifting gas, such as hydrogen, helium, ammonia, or methane, and stretches as it ascends into thin air. When the volume of the balloon has increased 30 to 200 times its original amount, the envelope ruptures, destroying the balloon.

B.

Zero-pressure balloons

The zero-pressure plastic (usually polyethylene) balloon is used to make measurements of the atmosphere as the balloon travels horizontally. The plastic balloon is filled only partly with gas while on the ground. As the balloon ascends, the expanding gas fills the envelope. This type of balloon has a valve that automatically discharges excess gas when the balloon reaches a certain altitude, so that the balloon can maintain this altitude as it travels horizontally. When the Sun sets, the gas cools, the volume decreases, and the balloon falls to the ground, unless ballast is released.

C.

Superpressure Balloons

The superpressure balloon is a rigid, nonstretchable balloon that is sealed with a plastic film to prevent the release of gas. It is also used to take horizontal measurements. By the time the balloon reaches its constant-altitude level, the gas in its envelope has become pressurized. Variations in the air pressure caused by the heat of the Sun produce changes in the internal gas pressure, but the volume of the balloon remains fixed. So long as the balloon remains under pressure, therefore, it continues to float at its predetermined constant-altitude level. Plastic films strong enough to withstand the high pressures within the balloon became available for use in about 1960. Flights of several months duration are possible with superpressure balloons.

D.

Uses of Scientific Balloons

Around the world each day balloons equipped with radiosondes make more than 1,000 different measurements of the wind, temperature, pressure, and humidity in the upper atmosphere (see Meteorology). These flights are made almost exclusively from land areas. As a result, measurements of the atmosphere are made over less than 20 percent of the globe. To obtain coverage over ocean areas, Global Horizontal Sounding Technique (GHOST) superpressure balloons have been flown experimentally from the Southern Hemisphere. These balloons fly with the winds, and their locations provide essential data about winds in the stratosphere above the oceans. The first flight around the world with a GHOST balloon was launched from Christchurch, New Zealand, in 1965 by a team from the National Center for Atmospheric Research (NCAR), based in Boulder, Colorado. The longest flight, floating at an altitude of 14 km (9 mi), lasted 744 days, circling the Earth more than 50 times.

Zero-pressure balloons, some as large as 150 m (500 ft) in diameter, carry scientific payloads of several tons to stratospheric altitudes. They are used in a variety of scientific applications. For example, such balloons can provide a platform for telescopes or radiation sensors to operate above the interfering atmosphere. Or they can act as a carrier for on-site measurements at altitudes higher than the capabilities of powered aircraft.

Zero-pressure balloons flying above 30 km (20 mi) are a useful platform for astronomical observations with infrared telescopes. Water vapor in the lower atmosphere interferes with viewing through infrared telescopes, but at an altitude of 30 km, water vapor is not a factor. Infrared telescopes have become essential in resolving such questions as the origin and nature of the universe, the birth of stars, and the physics and chemistry of interstellar matter. Cosmic rays, gamma rays, and high-energy X rays have also been studied from the high-flying, zero-pressure balloon platforms.

Zero-pressure balloons are an essential instrument for helping scientists understand the interactions between industrial chlorofluorocarbons (CFCs) and the stratospheric ozone layer, which absorbs harmful ultraviolet radiation from the Sun. Scientists believe that CFCs are destroying Earth’s protective ozone layer. Balloons provide the only platform capable of measuring the interactions between CFCs and ozone in this region 19 to 48 km (12 to 30 mi) above the Earth's surface.

Balloon platforms offer a low-cost alternative to satellite observations, but are limited by only one or two days of viewing because the measurement instruments are heavy and restrict the amount of ballast that can be carried. In the late 1990s the National Aeronautics and Space Administration (NASA) began a major effort to develop a superpressure balloon capable of carrying a 2,000 kg (4,400 lb) payload to an altitude of 40 km (25 mi) for up to 100 days. The Ultra-Long-Duration Balloon Program (ULDB), as the effort is called, requires the development of new film structures capable of handling the stresses of extended, high-altitude flight with heavy payloads. If this capability is realized, the balloon may become a low-cost alternative to some types of satellites.

For information regarding lighter-than-air craft equipped with apparatus for power and steering, see Airship.